Heartkiller
by Lady GreyWolf
Summary: post-Breaking Dawn.. Agent Elion Caspari is sent on a mission to catch the woman nicknamed Heartkiller. When joined by the Cullens, she realizes that things are far more complicated than they should be... Carlisle/OC, Caius/OC, smut and violence - you have been warned!
1. Prologue

"Signorina Elion Caspari."

She rose and smiled towards the nurse, a head shorter than her. The nurse gently smiled back, though she looked pretty scared. The woman sighed inwardly. Why couldn't people accept that some women were tall?

"This way, Signorina", the nurse continued, speaking English this time, and showed her towards one of the rooms.

The doctor was not much taller than her, with pale skin and blond hair. He smiled gently at her and greeted her in flawless Italian. She answered in the same language. Though she had to tell him that she was American when he started talking about her medical status. Such words she had not learned.

"Ah, well then", he said and switched language as easy as one switch the channel on TV. It surprised her to hear that his English was just as good as his Italian.

"How did you get these injuries?" he asked as he examined the deep wound in her left arm.

"I fell onto something while jogging in the woods", she answered. He glanced quickly at her face, as if to determine if she was lying or not. She grimaced.

"I know, I am extremely clumsy."

He smiled and seemed to let go of the subject.

"As far as I can see, you will be back to normal in a few weeks", he said and cleaned out the wound. She winced and fought back the urge to scream.

"Until then, be careful with what you do. Any more holes of a bullet… or a stick…"

She blinked at him in surprise, but he just continued to work with the wound.

"And I may have to amputate the arm", he finished. She nodded.

"Of course, I shall be very careful", she said. He walked over to the bench and brought out the tools he needed to close the wound.

"So how long are you in Italy?" he asked. She shrugged.

"Don't know yet, I'm here on personal business. Once they're finished off, I'll probably head back home."

"Then we have a common mission here", he said as he continued his work. "Me and my family are here on business as well. We hope it won't take too long to get things cleared up, but we'll see."

She nodded and watched him cover the scar with a white bandage.

"There", he said and smiled. She smiled back and rose from the chair she'd been sitting in.

"Thank you, doctor…"

She quickly read his name-tag.

"Cullen."

"You're welcome, Signorina Caspari."

She walked out of the room and made a mental note in her head never to bump into him again.


	2. Chapter 1

"You're back on track now, El?" Joseph Sereno asked. Elion nodded and examined the scar left from the wound.

"I am ready to continue, Sir."

"Good, your previous assignment has been taken by one of your colleagues…"

Elion cursed so low that he was unable to hear it.

"Though I've got something new for you right here."

She walked over to his computer and looked at the screen. With read letters it said _Heartkiller_.

"You're sure you spelled that right, Sir?" she asked. "Is it not supposed to be Heart_breaker_?"

"No, it's correct", Joseph answered. "The project is called _Heartkiller_, because that is what she is. A killer of hearts."

"So it's a woman?"

"A young one, I believe", Joseph said. "Witnesses and people who have survived her attacks have described her as someone who can manipulate your heart. She basically seems to bind her threat to some other person around her, possibly also a threat. And by binding I mean making them fall in love. Then she makes one of them kill themselves, by making him or her think that the partner is dead, and the other part is destroyed mentally by this, making him or her die as well."

"Clever, but mysterious", Elion said and nodded. "I will do all I can to stop her, and more."

"That's what I wanted to hear", Joseph said. "Here is a photo of her that one of her surviving victims carried with him."

Elion took the small piece of paper and studied the picture on it. Sure, the woman looked young, but something in her smile made Elion shiver. There was something extremely dangerous about this female creature, hidden behind her perfect façade.

"Any signs of her so far, Sir?" she asked Joseph. "I mean, she's been tracked, hasn't she?"

Joseph looked away.

"She has, yes, but a lot of our agents have been discovered very soon… and killed. Though one of them managed to give us some vital information. She is known to be hanging out at the _Bichiere da Vino_, the exclusive restaurant up in the north of this town. My advice is to start from there and look around."

Elion nodded and put the picture in her pocket.

At eight that evening she was placed at a table at the _Bichiere da Vino_. A table for one, she'd said, though the waiter had told her that she would have one more chair at the table, as it would not fit for the restaurant's design otherwise. 'Italians', she thought as she started to look through the menu.

While she was finishing off with the soup she'd ordered as a starter, the woman entered and sat down at an already prepared table. She smiled at the men that passed her and greeted several of the women as well, as if they were old friends. Elion continued to eat, but kept her senses alert and now and then looked up in her direction, even though her eyes often stopped on some other point. Every time, the woman was alone, not eating anything, not drinking anything, just looking around the restaurant.

Elion had just started on her main-course when the tall, blond man walked in through the door. She stopped eating at once and mentally burned her note about not seeing doctor Cullen again. It was him and he was heading towards the woman she was spying on.

He seemed relaxed as he talked to the graceful creature in front of him; she was the one tensing every now and then. Elion wondered if this was his unfinished business as well. Maybe his girlfriend, or boyfriend, had been one of her victims. She continued to watch the pair until Cullen rose and nodded, before turning. His gaze caught hers before she was able to turn away. 'Don't come here, just smile and walk out', she thought. But, of course, he had to walk over to her.

"Signorina Caspari", he said with a smile. She forced herself to smile back.

"How is your arm?" he continued.

"Back to normal", she answered. "Or almost, at least. Enough to work."

"That's good to hear", he said, before he stood still in silence. 'Alright, you got yourself into this mess', Elion thought and nodded towards the chair in front of her.

"Want to sit down?" she asked. He shot a quick glance towards the woman he'd talked to earlier, before he nodded.

"Why not?" he said and pulled out the chair.

"Can I get you anything?" she asked as he sat down.

"No, it's alright, I have already eaten", he answered and pulled off his coat.

"Well, something to drink, then?" she continued. "I feel rude to sit here and eat and drink while you do none of it."

He smiled.

"Don't worry, I'll be fine. And you are not rude since you asked if you should get me something."

She shook her head at him, before continuing to eat. While she did, he studied the restaurant, as if to find something, or someone. She studied him with curiosity.

"You're waiting for someone?" she asked when the waiter took away her empty plate.

"No", Cullen answered. "I'm keeping an eye on different people."

He smiled at her.

"Things in this city are not as they were before", he continued. "I suppose you have heard of the high count of dead people found lately."

'I'm working on that', she thought bitterly.

"Yes, I have heard about it", she said and nodded. "A serial killer is on the move, am I right?"

"Correct", Cullen said and nodded.

"And you are currently keeping an eye on different people that you consider to be possible murderers or victims?"

"Both", he answered. "I do hope that the killer is caught very soon."

She nodded and shook her head at the waiter. He bowed slightly and went to get her coat from the wardrobe.

"You're not ordering a desert?" Cullen asked.

"Would be rude, honestly, and don't argue about it", Elion answered. 'Besides, I'm working', she thought as she dressed.

"Well, if you say so", Cullen said. "Mind if I walk a bit with you?"

'Get away', she wanted to shout.

"No, that should be fine."

They left the restaurant side by side. Elion thought she saw the woman smile a bit as they passed her table.

After a few blocks, Cullen turned towards her.

"You have a far more dangerous work than I expected", he said silently. She blinked.

"I have?" she said. "What about what you did in there? You talked to the murderer, and don't tell me you do not know who she is."

Cullen looked away.

"I know her pretty well", he said bitterly. "Me and my family managed to stop her raid while we were back in America. We hoped that she would quit as she saw that people knew about her, but obviously not. And this time she is more discrete. I can not just walk up to the police and tell them about her, because I have no proofs to show them."

"So that is why you wanted to give me the information?" Elion asked with a snort. "So that she will be destroyed instead."

"No, I am telling you this so that you won't have anything to do about it", Cullen answered and turned towards her once again. "It is far too dangerous and you have no idea what you are trying to fight against."

"If you are talking about her manipulating my heart and such, I am sure I can find my way out of it", Elion answered grimly. "I work alone and she does not know about me yet, unless you made her see me by walking over to me."

"She is not human", Cullen hissed. Elion hesitated and let the words sink in.

"What did you say?"

"She is not human", Cullen repeated.

"You're kidding me", Elion huffed. "What is she then, a Marsian?"

Cullen growled. The growl did not fit with the rest of his personality that she had so far seen, it was not the kind doctor's growl, it was the growl of an animal. Unwillingly, she took a step back, away from him.

"You are human, Elion", Cullen said once he calmed down again. "Do not interfere with the world that is not yours."

"Well, that world is mine, since _humans_ have died because of her!" Elion yelled at him. "If there are two worlds in this one, one with humans and one with… other creatures, whatever they are, those worlds are combined into _one_. What happens in one of the worlds affects the other one just as well. They can not be separated and therefore I will interfere with this even though she turns out to be something I did not expect her to be."

He looked at her in silence, before he suddenly pulled her close and kissed her fiercely. His cold lips made her gasp in surprise.

"She is affecting you", she muttered once he pulled back.

"No, but she is trying to", he mumbled as he bent down to kiss her on the neck. "I can feel her… in the back of my head, she is trying to make me… fall for you…"

He looked at her with his golden eyes. She hadn't noticed that they were golden before, she had simply assumed that they were light brown.

"But it won't work", he whispered as he trailed a path of kisses from her ear down to her shoulder. "I love my wife… too much to ever… let her go."

"Then why are you doing this?" Elion whispered and bent back, her eyes closed as she played along.

"To make her believe that she has won", Cullen mumbled against her skin. She gasped as he played with her left ear with his tongue. It actually made him chuckle.

"You have to do it here?" she muttered as he continued.

"No, we can go to my place", he answered. "Much more… private…"

She smiled as she realised what he meant with that.


	3. Chapter 2

"Here we are", he said and let her into the suite of the luxurious hotel. She blinked.

"How much do you earn?" she asked and looked around. He smiled and pulled off his coat.

"There is something that you need to know", he said. "You might have guessed it already, though. I am not human."

"I had a vague guess about that, yes", Elion said and nodded. "Are you and her of the same race?"

"Not exactly", Cullen answered. "She is half-human, I am not. I am a complete… complete vampire."

Elion took a step away from him.

"A vampire?" she spit out.

"Not like in the movies and old tales", Cullen said. "I do not drink human blood. I am what we call a vegetarian. Only animals for me."

"So I am… safe? You did not make me come with you just to kill me?"

He shuddered.

"No, definitely not."

She nodded slowly and sat down on a chair.

"And she? Does she drink blood?"

"I do not think so", Cullen answered and pulled the curtains close. "I do believe that she is able to, but that she prefers not to, as she finds it too animalistic. She is probably the worst kind of diva you will ever find."

"And she shows it by making people fall in love and die", Elion muttered. Cullen nodded and seemed to sniff the air.

"She is close", he said. "Two blocks away, at the most."

"Now that is a tool that I would like to use", Elion said and smiled. "Knowing the smell of people and being able to sense them from far away."

Cullen did not look as amused.

"You have to tell me if you sense anything that might lead somewhere where we can not go", he said. "I might be able to push her out of my own mind, but I can not do it for you. If you start feeling something for me, tell me and leave at once. That's the best thing we can do of this situation."

"Sounds good", Elion said and nodded. Cullen walked over to her, kneeled by her chair and kissed her again. When he released her, she tried to speak but he silenced her by putting his finger over her mouth.

"Play along and stop me if I go too far", he mumbled in her ear. "Then I might be affected as well."

His cold lips found hers again, his tongue forcing its way into her mouth. She moaned, unwillingly, at the feeling; it had been a long time since she had been with a man. That fact was what made it hard to push him away, to ignore the slight tickle in her mind that she assumed was the work of the woman outside; the soft voice telling her to give in.

Cullen ripped her blouse open, the buttons flying over the room, and with one last kiss on her swollen lips he bent his head and grazed her chest with his sharp teeth. She gasped, her back arched and she heard him moan softly.

"Doctor Cullen", she hissed. Her calling him that made him even more urgent and his head went further down as he let his tongue make patterns on her stomach. Meanwhile his cold hands moved up her thighs, in beneath her skirt. The feeling was unbelievable.

"Oh God", she whispered, trying to focus. "You know this isn't making things easier, do you?"

"Yes", he answered, his lips still against her stomach. She shivered.

"Tell me if I go too far."

She was about to answer when he rose, scooped her up and moved her to the bed, all in the speed of light. Him being above her, she pulled him down for another kiss as she unbuttoned his shirt. He moaned against her lips when her hand finally touched his skin, the cold stone-hard muscles of his stomach.

It was easy to see people falling for vampires just because of that; that feeling of those muscles beneath your warm hand was intoxicating.

Elion let her fingers trace their outlines as the blond doctor continued to kiss her, then moved down to undo his trousers. He chuckled.

"Unfair, I'm not done with you yet", he said, looking at her with eyes that had now turned black.

"Are you sure she's not affecting us?" Elion asked. He smiled and dipped his head down so that it rested right next to hers.

"Yes", he said. The next moment he pushed her skirt up, tore her panties into pieces and put two fingers into her. She gasped and arched her back yet again.

He pulled out, almost all the way, before he pushed in again.

"Oh yes!" she hissed. He chuckled and did the same thing again. She grabbed onto his pants and gave one quick tug, making them and his underwear fall before he was able to stop them. A grin spread on her face at the size of him.

"You little minx", he said and pulled out his fingers, licking her juice from them as he did. Then he kicked his pants away, unbuttoned her bra and lay down on top of her, yet again in one quick motion.

"You want to do this?" he asked, his voice soft.

"Just do it", she answered. The next moment he entered her, filling her completely with his large member. She put her legs around him, wanting him to get deeper.

Except for moans and groans, their act was silent. No pleas, no words of love, just animalistic sounds, because that was what it was to them; purely animalistic. There was no love, this was just business.

Elion fell asleep in his bed after they were done, not noticing him get up, get dressed and place himself in a chair, talking softly on the phone as he watched her sleep.


	4. Chapter 3

The shining sun woke her the next day and she felt strangely rested. With a curse she blamed herself for sleeping so long, before she remembered what had happened the night before

She sighed and leaned back against the pillows, rubbing her face with both hands.

"Hi."

She sat up with a surprised yell, only to find a small, black-haired teenage girl sitting in one of the chairs, looking amused.

"I'm Alice", she said. Elion realized that also this girl had golden eyes and groaned.

"Another vampire."

"Yep, I'm Carlisle's adoptive daughter", the girl said, jumping up from her seat. "And I'm going to get you ready for the party."

"What blasted party?" Elion asked, staring at the large trunk that the girl had just opened.

"The victory-feast", Alice answered. "You and Carlisle enabled the rest of us to catch Fiona last night."

"Fiona...?"

"You know, that woman", Alice said, considering her for a moment. "No, wrong tone of blue."

"Look, I'm perfectly capable of dressing myself", Elion said.

"No use", another voice said. A brunette had just appeared through the door, also golden-eyed.

"When Alice gets going, there's nothing that can stop her", she continued as she sat down by the desk. "Believe me, I've been there too many times."

"And only God knows what would have happened if I didn't help you pick out decent clothes", Alice said, smiling before she dashed over to the side of the bed, holding a bundle of clothes in her arms.

"I'm not wearing pink", Elion protested.

"Oh yes you are", Alice said. The brunette rolled her eyes and Elion realised that it was better to just get over with it. The sooner she parted with this weird family the better.

When Alice was done with her she was wearing a black sleeve dress that reached the middle of her thighs and a light pink bolero, along with a pair of shoes that Elion thought of as extremely uncomfortable.

"You'll get used to it", Alice said and skipped out of the room. The brunette, whose name was Bella, looked sympathisingly at Elion before she followed her friend.

Elion sighed and got up to stand in front of the mirror. In her opinion she looked ridiculous; this dress was definitely not appropriate for her kind of work. She pulled at it, trying to make it look somewhat better, but failed.

"I see Alice got to you."

The soft voice coming from the door made her twitch slightly, but all years of training with the CIA helped her keep her control in all kinds of situations.

"I'm not much for dresses", she said, wrinkling her nose slightly at the image. The honey-blond vampire came up behind her, his image smiling slightly.

"You look great", he assured her. "And it's only for tonight. Then we will part, carry on with our own lives."

Elion nodded and turned around to face him.

"I just want to assure you that I am not falling for you", she said sharply. "You can smile all you want at me, but even after last night I won't fall for you. Got it?"

He chuckled.

"As I told you last night; I love my wife too much to ever let her go."

He held out his arm to her and after some consideration she took it, allowing him to lead her out of the suite and up one set of stairs.

They were now standing in an amazing restaurant, but what was even more amazing was that it was empty, except for nine people standing in the middle of the room. Seven of them were just as pale as the doctor next to her, one of them had a more normal skin-tone and the last one was probably a Native American.

"Here she is", Carlisle Cullen announced as he led her forth. "The heroine of last night."

"It's lovely to meet you, Elion", a woman with caramel coloured hair said as she stepped forward and gave the human a hug.

"Elion, this is my wife, Esme", Carlisle introduced as they parted. "And then there's Alice, whom you've already met, and her mate Jasper, Bella with Edward and Rosalie with Emmett."

"Nice to meet you all", Elion said, memorizing their names. Then Carlisle turned her around to face the two last ones.

"And this is Jacob Black", he said, pointing at the tanned Native American. Elion wondered how it was even possible for him to fit in a suit; he was both tall and _very_ muscular.

"He is the leader of a pack of shapechangers", Carlisle continued. She frowned.

"Seriously?"

"Yep", Jacob said and grinned. "Me and the rest of the group trapped that little diva between us and the Cullens. You sure created a good distraction last night."

"Jake", Bella said warningly, but the boy just kept grinning.

"And this, Elion, is Renesmee", Carlisle said and pointed at the girl next to Jacob. "She is the daughter of Edward and Bella."

"But isn't it impossible for vampires to... reproduce like that?" Elion said, noticing the similar features between Renesmee and her parents. Oh yes, she was definitely their biological child, but she was still not a vampire.

"I'm a half-blood", Renesmee said with a smile. "I was born before my mother became a vampire."

Elion felt like she was about to throw up, her head was spinning with all of the information given to her. She noticed how the vampire family eyed her with concern.

"She's going to throw up", the blond male, Jasper, said. Carlisle swooped her up at once and rushed her into the bathroom, where she spit out whatever her stomach contained.

When she was done, she noticed how concerned Carlisle looked.

"Look, it's nothing", she said sharply. Carlisle shook his head.

"It is something", he answered. "You're pregnant."

Elion stared at him before she burst out laughing.

"Alright, then you are definitely the most insane..."

"Elion, listen to me", Carlisle interrupted her, grabbing her by the shoulders. "You have a vampire child inside of you, a half-breed just like Renesmee. I made you pregnant last night and since such a child develops quicker than a human one..."

He didn't finish the sentence, he just looked at her before he released her.

"I'll get it out of you, I promise."

**Author's note: reviews are luv! Honestly, they are my inspiration and my strength, so if you like the story and want to read more, please post a review!**


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